The present invention refers to a fluid acquistion/transfer layer in an absorbent article, such as a diaper, pant diaper, incontinence guard, sanitary napkin, panty liner or the like.
An absorbent article usually comprises several layers, a fluid pervious topsheet intended to be worn in contact with the wearer, a fluid acquisition/transport layer for quickly acquiring body fluids, an absorbent core for absorbing and storing the body fluids and a liquid impervious backsheet. The fluid acquisition/transport layer has an open porous structure and it shall be able to quickly receive and temporarily store a certain amount of fluid and transfer it further to the underlying absorbent core. The fluid acquisition/transport layer usually is a so called high loft material produced by carding and thru-air bonding or needling a synthetic fibers, such as polyester, polypropylene or mixtures thereof. It could also comprise a porous foam material. Examples of absorbent articles comprising a porous fluid acquisition/transport layer are found in U.S. Pat. No. 3,371,667, EP-A-0,312,118, EP-A-474,777 and U.S. Pat No. 5,556,392.
The use of heat-shrunk, spiralized, thermoplastic bicomponent fibers of a side-by-side type in a topsheet material is disclosed in the intermediate document PCT/SE97/02074. The fibers should be very thin, 1.5-3.3 dtex, in order to be soft against the skin of the wearer since they are used in the topsheet of an absorbent article. The topsheet may further comprise heat-activateable bonding fibers which have been bonded together by heat treatment. Such spiralized bicomponent fibers of side-by-side type provides an open and lofty structure which is very resilient also after compression. Heat shrinkage and spiralization of the fibers can be provided by the supplier or in-line during manufacture of the transfer layer.
EP-A-0 729 735 discloses a topsheet in an absorbent article comprising eccentric bicomponent fibers which crimp when heated. They have a length of 3-12 mm and are dry formed on top of the absorbent core. Heat treatment then is performed in order to crimp the eccentric bicomponent fibers and to bind them together. Such bonding of the crimped fibers will seriously detoriate their resiliency.
EP-A-0 306 262 and GB-A-2 214 201 further disclose absorbent structures in e g diapers and sanitary napkins, which comprise crimped fibers in order to give resiliency to the structure and resistance to folding during use of the absorbent article.
The object of the present invention is to provide a fluid acquistion/transfer layer having an open and lofty structure which is very resilient after compression and which layer is effective in receiving and temporarily storing body liquids and transfer is further to the underlying absorbent core. This has been accomplished by the fact that said fluid acquisitionl/transfer layer comprises a mixture of heat-shrunk, spiralized, thermoplastic multicomponent, preferably bicomponent, functional fibers of 3.4 dtex or more, in which the components of said fibers have mutually different shrinkage properties and are located in a side-by-side relationship, and thermoplastic bonding fibers which have been bonded together by heat treatment, while said functional fibers are substantially unbonded by said heat treatment.
Further features of the fluid acquistion/transfer layer according to the present invention are stated in the claims and in the detailed description below.
The invention also refers to an absorbent article such as a diaper, pant diaper, incontinence guard, sanitary napkin panty liner or the like, comprising a liquid pervious topsheet, a liquid impervious backsheet, an absorbent core and a fluid acquisition/transfer layer arranged between the topsheet and the absorbent core, wherein said fluid acquisition/transfer layer is of the kind stated above.